#1 WWE's doors seem to be open for both of them in the future
After CM Punk's comments on Colt Cabana came out in the open, Vince McMahon apologized to the disgruntled Superstar and said that he is willing to work with Punk. 3 years later, Dave Meltzer stated that WWE is willing to have Punk back and would welcome him with open arms. Recently, it was reported that WWE is stil open for Punk to return. It's no secret that WWE has reconciled with Superstars we thought we would never see again, and the same seems to be the case with CM Punk.
Also read: 5 WWE Superstars who forgot the script
As far as Ambrose goes, he was a part of hands down the greatest faction in modern history, The Shield. WWE can't possibly reunite The Hounds of Justice if there's no Dean Ambrose in the picture. The group has been a mainstay on WWE's main event scene for a while, and has made the company tons of money. An Ambrose return would open up a bunch of possibilities for feuds, merchandise, and dream matches. This is the major reason WWE will welcome back Moxley if he is interested.